1. Field of the Invention
This invention relates to a heat transfer bag useful for the dissipation of heat from electronic components such as integrated circuits, wherein the bag includes a thermal via for enhancing transfer of heat from the component to heat transfer liquid within the bag.
2. Description of the Related Art
Thermal management of electronic systems has conventionally been accomplished by the use of fans, metal heat sinks, or both. Fans, for instance, provide forcedair convection cooling, and heat sinks dissipate thermal energy from components by conduction. However, it is sometimes difficult to provide sufficient cooling for components within compact or densely arranged electronic systems. Moreover, fans often produce an unacceptable level of noise.
A recent development that has been found to efficiently transfer heat in compact electronic systems is the thermal transfer bag, also known as the Liquid Heat Sink bag available from Minnesota Mining and Manufacturing Company, assignee of the present invention. The bag is made of a sheet of flexible, durable, air-impermeable material and is filled with a thermally conductive, chemically inert, essentially gas free body of liquid which comprises fluorochemical liquid. The bag is placed between the heat-generating component and a heatdissipating surface, and conduction through the liquid as well as some movement of liquid within the bag due to convection currents transfer heat from the component to the heat-dissipating surface.
The aforementioned thermal transfer bag is advantageous in that the flexible material geometrically conforms to the configuration of the cavity within the electronic equipment, and comes into intimate contact with heat-generating components and the heat-dissipating surface to establish a thermal path therebetween. In some applications, the inherent shock-absorbing nature of the filled bag functions as a packing or cushion to protect the component from physical shock damage. The bag can easily be removed and replaced in the field during repair, and may optionally be provided with an adhesive to hold the bag in place.
There is a continuing desire, however, to increase the rate of transfer of heat away from heat-generating components in electrical devices, particularly in instances where the components produce relatively large amounts of heat or where there is a need to reduce the overall size of the device. By increasing the rate of heat transfer, heat-generating components may be spaced closer together with other components while still enabling each component to properly function within a desired temperature range of operation.